1. Field of the Invention
This invention relates to a leaf chain and relates particularly to a leaf chain applied to a high-loading transmitting mechanism.
2. Description of the Related Art
A general chain is mainly designed for a purpose of the power transmission. The chain varies in types and structures to fit for different using fields.
A Leaf chain is applied to a mechanism for transmitting and hoisting heavy objects currently. Referring to FIG. 1 showing a conventional leaf chain 1 composes a plurality of connective chain units 11. Each chain unit 11 includes two aligned pins 12, at least two outer plates 15 disposed around the pins 12, a plurality of first inner plates 13 disposed around the pins 12 and located between the two outer plates 15, a plurality of second inner plates 14 disposed around the pins 12 and located between any two first inner plates 13, a plurality of bushings 17 mounted around the pins 12 and located in the first and second inner plates 1314, and a plurality of washers 16 mounted around the pins 12 and located between the first and second inner plates 1314 and between the first inner plates 13 and the outer plates 15. A plurality of first and second apertures 131141 are respectively formed through the first inner plates 13 and the second inner plates 14. The bushings 17 are disposed between the first apertures 131 and the pins 12 and between the second apertures 141 and the pins 12. Each of the second inner plates 14 are located at a place corresponding to each of the outer plates 15. The outer plates 15 having a plurality of third apertures 151 are fixed tightly on the pins 12. The lubricant moistens a space between each pin 12 and each bushing 17 to prevent the pins 12 and the bushings 17 from being attrite and rusted during a transmitting process (not shown).
However, the disclosed leaf chain 1 still has problems. Because the outer plates 15 engage tightly with the pins 12, the large force concentrates on the outer plates 15 to cause the deformation of the outer plates 15 during the transmitting process. Meanwhile, when the leaf chain 1 rotates under a high-loading state, the pins 12 rotate abnormally because the twisting force is larger than the tight engagement between the outer plates 15 and the pins 12 to cause the outer plates 15 and the pins 12 to be worn away. Moreover, the outer plates 15 are even stretched and deformed to affect the operating life of the leaf chain 1.
Generally, the leaf chain 1 keeps operating in a specific transmitting direction and twisting angle. Besides, the outer plates 15 are fixed tightly with the pins 12. The pins 12, therefore, link with the outer plates 15. Thus, the attrite parts of the pins 12 and the bushings 17 are centered on the specific part of the pins 12 to cause the unequal contact of the pins 12 with the bushings 17. Gradually, the specific part of the pins 12 which takes the applied force is recessed and deformed to reduce the operating life of the leaf chain 1.
Moreover, the washers 16 are disposed between the first and second inner plates 1314 and provide the sealing effect by being tightly disposed to the first inner plates 13 and the outer plates 15. However, the first inner plates 13, the second inner plates 14, and outer plates 15 respectively twist in the different angles to easily cause the attrition and damage of the washers 16 disposed between the first and second inner plates 1314 and between the first inner plates 13 and the outer plates 15 to lose the lubricant.